In chemical process industries effluent streams containing various levels of organic byproducts are generated which must be purified or treated prior to their discharge to the environment. Technology which is referred to as wet oxidation, is finding new applications for the destruction of organic material in these effluent streams. Traditionally, wet oxidation involves the contacting of organic compounds dispersed in an aqueous medium with an oxygen-containing substance at elevated temperatures and pressures wherein the organic compounds are converted to carbon dioxide and water. Representative patents which show the wet oxidation of organic substances in aqueous mediums at elevated temperatures are as follows:
U.S. Pat. No. 4,141,829 discloses a process for the oxidation of organic substances which are dissolved or dispersed in an aqueous stream utilizing molecular oxygen as the oxidant. Combustion of the organic components is carried out in a two phase system under liquid phase conditions. To maintain liquid phase conditions, the pressure in the reaction zone is adjusted such that it is higher than the vapor pressure of water, e.g., 1 to about 1.3 times the partial pressure of steam. To avoid precipitation of salts, if salts are present in the stream, the reaction is carried out at a pressure sufficient to prevent substantial evaporation of the water. Temperatures for wet oxidation of the waste range from 150.degree. to 370.degree. C. and pressures range from 5 to 235 bars.
U.S. Pat. No. 4,543,190 discloses a method for oxidizing organic materials by wet oxidation wherein oxidation is effected in a reaction zone maintained at a temperature above the critical temperature for water (374.degree. C.) and at a pressure of at least 220 atmospheres. Destruction of organic material in streams having from 2 to 25%, by weight organic material is accomplished.
U.S. Pat. No. 4,113,446 discloses a wet oxidation process for converting solid and liquid organic materials to high BTU gas with little tar formation. The reaction is carried out at a temperature and pressure equal to or exceeding the critical temperature and pressure for water. When the solid or liquid organic material is intimately mixed with the water at temperatures above the critical temperature of water (647.degree. K.) and above the critical pressure (218 atmospheres) reforming occurs rapidly and product gas is obtained from the reaction zone at high pressure.
U.S. Pat. No. 4,145,283 discloses a process for the purification of a wastewater stream containing organic by-products from the synthesis of hydroxy aromatics by means of a caustic soda melt. The organics are oxidized at temperatures of 100.degree.-370.degree. C. at pressures of from 1-300 bars.
U.S. Pat. No. 4,853,136 discloses a process for oxidizing organic material in a polyphase tubular reactor at temperature conditions of 50.degree.-370.degree. C. and below the critical temperature and a pressure below the critical pressure from 2-210 bars. A plurality of injections are made in the polyphase tubular reactor.
To summarize the prior art, wet oxidation of organic contaminants in waste streams at elevated temperature and pressure is rather common and can be accomplished without substantial difficulty. Difficulties arise, however, in the treatment of waste streams containing substantial levels of inorganic components or salts. Other difficulties also exist in the treatment of organic contaminants containing inorganic salts in tubular reactors.